77. The union which we conceive in distinct substances is either juxtaposition in space, simultaneousness in time, or the concourse of forces producing a common effect: juxtaposition in space or simultaneousness of time does not help us to explain thought, the act of the will, nor any internal phenomena; and neither does the concourse of forces producing a common effect solve the problem. On this supposition we should have to conceive internal phenomena as the products of an elaboration to which various substances have occurred. Let us for a moment admit this absurdity; we advance nothing by it, for we then ask, where does the phenomenon reside? If in all the substances jointly it must be in itself composite, and its consciousness would also be composite; none of the component substances could say _I_ with respect to this phenomenon; there would, therefore, be a multiplicity of consciousnesses. Either these consciousnesses would be united in a point in order to form a common consciousness, or they would not. If they are united, their point of union must be a simple substance, or we relapse into the multiplicity of consciousnesses: if they are not united, the different internal consciousnesses of each man will be like the consciousnesses of different men; each substance will think its own, without knowing what the other thinks. 78. Finally, this divisibility of substance and of consciousness will extend to infinity, or it will not; if the former, instead of one thinking being, there will be an infinite number of thinking beings within each one of us; if the latter, we must come to simple substances with thought and consciousness, which is precisely what our adversaries are opposed to. Infinite divisibility does not save them from simplicity; the division separates the parts, but it supposes them distinct; therefore, infinite division must suppose an infinite number of simple beings which make the division possible. CHAPTER XII. KANT'S OPINION OF THE ARGUMENT PROVING THE SIMPLICITY OF THE SOUL. 79. Kant calls the argument, by which we have just proved the simplicity of the soul, the second paralogism of psychology. He gives it in these terms: "Every thing, the action of which can never be conceived as the concurrence of many agents, is simple: the soul or thinking substance is of this nature; therefore the soul is simple." The German philosopher admits that this argument is not a mere sophism, invented by some dogmatist for the purpose of giving his assertions a slight appearance of truth; and he confesses that it seems to defy the most attentive examination and the most profound reflection. Still he flatters himself that he can expose its fallacy, showing that this principal support of rational psychology is a false foundation, and that, consequently, the whole edifice of this science is built in the air.